his article discusses the distributed solar power deployment initiative at the university of the Virgin islands (uVi). it is an ongoing project that will deploy 3.3 MW of solar power at uVi. the project needs, benefits, design, and financing for the initiative are discussed. uVi is

located in the u.s. Virgin islands. a brief introduction to the u.s. Virgin islands is presented first, providing background information on the energy need and why the solar power deployment initiative is necessary for uVi.

The U.S. Virgin Islandsthe u.s. Virgin islands are an organized, unincorporated u.s. territory on the boundary of the North american plate and the caribbean plate. about 40 mi east of Puerto rico and immediately west of the british Virgin islands, the u.s. Virgin islands are geographically part of the Virgin islands archipel-ago and are located in the leeward islands of the lesser antilles (Figure 1).

Digital Object Identifier 10.1109/MELE.2014.2380031 Date of publication: 27 February 2015

Islands in the Sun

The solar power deployment initiative at the University of the Virgin Islands.

By Wayne Archibald, Zuyi Li, Mohammad Shahidehpour, Steve Johanns, and Tom Levitsky

T

2325-5987/15©2015IEEEIEEE Electr i f icat ion Magazine / March 201556

image courtesy of wikimedia commons/ryansmith714

the u.s. Virgin islands are located in the atlantic standard time zone and do not participate in daylight saving time. When the mainland united states is on standard time, the u.s. Virgin islands are 1 h ahead of eastern standard time. When the mainland united states is on day-light saving time, eastern daylight time is the same as atlantic stan-dard time.

Geographythe u.s. Virgin islands consist of the main islands of saint (st.) croix, st. John, and st. thomas, along with the much smaller but historically distinct Water island, and many other sur-rounding minor islands. the main islands have nicknames often used by locals: “twin city” (st. croix), “rock city” (st. thomas), and “love city” (st. John). the combined land area of the islands is 133.73 mi2, roughly twice the size of Washington, d.c. the u.s. Virgin islands are known for their white-sand beaches. Most of the islands, including st. thomas, are volcanic in origin and hilly. the highest point is crown Mountain, st. thomas (1,555 ft).

Climatethe u.s. Virgin islands have a tropical climate, moderated by easterly trade winds and with relatively low humidity. Natural hazards include earthquakes and tropical cyclones (including hurricanes). temperatures vary little throughout the year. statistical temperature and precipitation data are shown in table 1 and Figure 2. in the capital city of char-lotte amalie in st. thomas, the typical daily maximum temperatures are around 91 °F in the summer and 86 °F in the winter, and the typical daily minimum temperatures

are around 78 °F in the summer and 72 °F in the winter. rainfall averages about 39 in per year. rainfall can be quite variable, but the wettest months on average are september

to November, and the driest months on average are February and March. the u.s. Virgin islands are subject to tropical storms and hurricanes, with the hurricane season running from June to November. in recent history, substantial damage was caused by hurricane hugo in 1989 and hurri-cane Marilyn in 1995.

Economythe u.s. Virgin islands are an inde-pendent customs territory from the mainland united states and operate largely as a free port. tourism is the primary economic activity (Figure 3). the islands normally host 2 million

visitors a year, many of whom visit on cruise ships. the manufacturing sector consists mainly of rum distilling. the agricultural sector is small, with most food being imported. international business and financial services are a small but growing component of the economy. to draw more technology-focused companies and expand this segment of the economy, the government founded and launched uVi research and technology Park in conjunction with private businesses and uVi.

the aggregate population of the u.s. Virgin islands is estimated to be approximately 109,000. about 42% of the population is between the ages of 25 and 54. the median household income, adjusted for inflation, is approximately us$32,000, well below the current u.s. average of about us$50,000. the poverty rate is relatively high in the u.s. Virgin islands. u.s. census data indicate approximately

PPA is a financing arrangement that allows UVI to purchase solar electricity with little to no upfront capital cost.

IEEE Electr i f icat ion Magazine / March 2015 57 IEEE Electr i f icat ion Magazine / March 2015 57

IEEE Electr i f icat ion Magazine / March 201558

29% of families and 33% of individuals live below the pov-erty line. this can be compared with a 2009 poverty rate of approximately 14% for the united states.

Electric Transmission and Distribution Systemst. thomas and st. John are part of one interconnected power system, with an installed capacity of 191 MW, a maximum load of approximately 88 MW, and a minimum load of about 50 MW. the island of st. croix constitutes a second power sys-

tem, with an installed capacity of 117 MW, a maximum load of approximately 55 MW, and a minimum load of about 35 MW. although the topography of the ocean floor has pre-vented the direct interconnection of these two grid systems to date, studies are underway to examine the possibility of connecting both island systems with Puerto rico and the british Virgin islands (Figure 4). the grid infrastructure of the u.s. Virgin islands consists primarily of subtransmission lines (25–115 kV). the two grid systems currently operate at

(a)

(b)

Figure 1. The U.S. Virgin Islands: (a) St. Thomas and St. John and (b) St. Croix. (Images courtesy of Google Maps.)

Table 1. climate Data for St. Thomas, U.S. Virgin Islands. (Source: weather.com.)

January February March April May June July August September October November December Year

Record high (°F) 93 93 94 96 97 99 98 99 98 97 95 92 99

Average high (°F) 85 85 86 87 88 89 90 90 90 89 87 86 87.7

Average low (°F) 72 73 73 74 76 78 78 78 78 77 75 74 75.5

Record low (°F) 63 62 56 62 66 67 57 59 64 66 52 62 52

Precipitation (in) 2.38 1.48 1.42 2.74 3.06 2.53 2.85 3.74 5.58 5.42 5.23 2.96 39.39

IEEE Electr i f icat ion Magazine / March 2015 59

24.9 and 34.5 kV for st. thomas and st. croix, respectively. st. croix is currently in the process of upgrading parts of its sys-tem to operate at 69 kV. the distribution systems are typically operated at 13.8 kV. the total technical and nontechnical loss-es were estimated at 6% on the st. thomas–st. John system and more than 13% on the st. croix system.

Energy Costsimilar to many island communities, the u.s. Virgin islands are 100% dependent on imported fuel oil for electricity. retail electricity rates in 2011 reached as high as us$0.49/kWh and were as high as us$0.52/kWh following the oil price spikes of 2008. the electricity generation and distribution systems in the u.s. Virgin islands are owned, operated, and maintained by the Virgin islands Water and Power authority

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Figure 2. The monthly climate data for St. Thomas, U.S. Virgin Islands: (a) temperature and (b) precipitation. (Source: weather.com.)

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Figure 4. The conceptual interconnection between the U.S. Virgin Islands, Puerto Rico, and the British Virgin Islands. (The line information is from a public report: http://www.viwapa.vi/AboutUs/Projects/ProjectDetails/11-08-02/USVI-BVI-Puerto_Rico_Interconnection.aspx. Map image courtesy of Google Maps, illustration added.)

Figure 3. Tourism is the primary economic activity in the U.S. Virgin Islands, which are known for their white-sand beaches. (Photo courtesy of http://www.imagebrowse.com/us-virgin-island-backgrounds/.)

IEEE Electr i f icat ion Magazine / March 201560

(WaPa). WaPa generation assets are primarily located on st. thomas and st. croix and consist of steam turbines operat-ing on number 6 fuel oil, combustion turbines operating on number 2 fuel oil, and a limited amount of internal combus-tion (diesel) generation. capacity is derived primarily from combustion turbines (72%) and steam turbines (28%). the mean household size in the u.s. Virgin islands is 2.2 people. the total per-capita electricity consumption, including losses and water production, is estimated to be the equivalent of 8,000 kWh per per-son per year. thus, the total annual household electricity consumption is about 17,600 kWh. With an average price of us$0.51/kWh for electricity, the total annual household electricity expenditure amounts to us$8,976, which is about 28% of the median household income (us$32,000). this extremely high cost of energy has seriously stifled the economic development of the u.s. Virgin islands.

Generation Efficiencybecause of the use of low- and high-pressure steam for desalination, coupled with outmoded controls and non-standardized operations procedures, WaPa’s generation fleet operates at a relatively inefficient heat rate (greater than 15,000 btu/kWh). this can be compared with the heat rate for Guam, an island in the south Pacific that also relies on number 6 and number 2 fuel oil and had a system average heat rate of 9,720 btu/kWh, or hawaii,

whose heat rate has been estimated at 10,500 btu/kWh. to enhance the efficiency of existing generation assets, WaPa installed waste heat recovery steam generators (hrsGs) in st. thomas in 1997 and st. croix in 2010. WaPa intends to upgrade the st. thomas hrsGs to

increase efficiency but has not yet established a time frame in which to complete these upgrades.

Solar Energythe sun in the u.s. Virgin islands is strong. the solar radiation map in Fig-ure 5 shows that the u.s. Virgin islands have a good solar resource for solar photovoltaic (PV) generation, with an average solar irradiation greater than 5.7 kWh/m2/day. thus, solar energy has the potential to make a meaningful contribution to the u.s. Virgin islands’ energy future if it is widely deployed. the National renew-

able energy laboratory estimates that, under a base case scenario, 10 MW of solar PV will be deployed by 2025, which represents between 7% and 10% of peak load.

Wind Energythe consistency of the trade winds from the east provides an excellent source of untapped power in the u.s. Virgin islands. this resource is particularly pronounced along the southern coastline and exposed ridges of the islands (Figure 6). the National renewable energy laboratory estimates that, under a base case scenario, 22.5 MW of wind will be deployed by 2025, which represents between 15% and 20% of peak load.

St. Thomas

Anna’s Retreat

Charlotte AmalieCruz Bay

St. John

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Christiansted

Grove PlaceFrederiksted Southeast

0 5 10 km

Annual Average of Daily Sun

<5.6 5.8> kwh/m2

Figure 5. The solar radiation of the U.S. Virgin Islands. (Source: Clean Power Research.)

Solar energy has the potential to make a meaningful contribution to the U.S. Virgin Islands’ energy future if it is deployed widely.

IEEE Electr i f icat ion Magazine / March 2015 61

a look at UVIFounded in 1962, uVi is a public, coed, land-grant, historically black university that lies in the heart of the beautiful caribbe-an. approximately 2,500 students are enrolled on the two campuses (Figure 7): the albert a. sheen campus on

st. croix and the st. thomas campus. uVi offers 38 under-graduate degree programs and seven graduate degree pro-grams across its five colleges and schools. in a tropical climate, uVi students enjoy indoor and outdoor activities year round. student entrepreneurs are rewarded with startup

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3935302723

5.5<5.5

*Net Capacity Factor Assuming 12% Energy Losses

The anual wind speed estimatesfor this map were produced byAWS Truewind using itsMesomap system and historicalweather data.

0 5 10 km

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U.S. Department of Energy National Renewable Energy Laboratory

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Figure 6. The annual wind speeds of the U.S. Virgin Islands: (a) St. Thomas and St. John and (b) St. Croix. (Source: National Renewable Energy Laboratory.)

Figure 7. The two campuses of UVI: (a) the Albert A. Sheen Campus, St. Croix, and (b) the St. Thomas Campus. (Images courtesy of UVI.)

IEEE Electr i f icat ion Magazine / March 201562

funds. students in the science, technology, engineering, and mathematics area present their research locally, nationally, and internationally. internships give students hands-on field experience. student clubs and organizations offer students the opportunity to lead, work as a team, network, and serve the commu-nity. the uVi experience is uniquely multicultural, international, entrepre-neurial, and intellectually stimulating. uVi provides a vital and exciting envi-ronment for educating future leaders of the global 21st-century community. table 2 summarizes the enrollment of uVi in fall 2012.

the caribbean Green technology center (cGtc) at uVi was created in 2011 to advance energy and environ-mental sustainability in the u.s. Vir-gin islands and their neighbors throughout the caribbean basin. in the face of severe economic pressures and energy and water insecurity, the cGtc serves as an important clear-inghouse for information and pro-cesses geared toward supporting and protecting natural resources and the development of alternative and renewable-energy technologies. the cGtc serves as a vibrant intellectual hub for learning, networking, and inno-vation in and across the caribbean, in all areas pertaining to green technology. its main purpose is to foster research, education, and public service on sustainability; promote caribbean interislands cooperation; advance interdisciplin-ary investigations and learning; collaborate with govern-

mental agencies and industry partners; and research, develop, demonstrate, and monitor green technology. the cGtc addresses scientific, policy, and implementation issues around the topic of green technology and sustain-

ability, especially as it pertains to liv-ing in the caribbean. it brings togeth-er groups of researchers, industry leaders, and policy makers to address and solve problems and implement solutions that lead to better lives for the people of the caribbean.

in an attempt to reduce energy consumption, uVi started examining firms to provide alternative renew-able- energy solutions. in the field of renewable energies, there are solar, wind, biomass, water, geothermal, and hydrogen and fuel cells. Previ-ously, wind turbines were researched. because of the maintenance required for these units during hurricane sea-son, it was determined that any wind project would not be feasible. thus, a request for qualifications was adver-tized to explore firms that could pro-vide a power purchase agreement (PPa) for a PV system. the PV systems

could be ground mounted, rooftop mounted, carport inte-gration, or a combination of all three. any option would be rated to the Florida hurricane standards for 150-mi/h winds and gusts and would not require additional maintenance during hurricane season. the systems would tie into the uVi power grid to support as much electrical consumption as possible.

Table 2. UVI enrollment by level, campus, Status, and Gender, Fall 2012. (Source: UVI.)

All Full Time Part Time

Level Total Female Male Total Female Male Total Female Male

UVI (All)

Undergraduate 2,271 1,589 682 1,423 969 454 848 620 228

Undergraduate 184 145 39 50 33 17 134 112 22

Graduate 2,455 1,734 721 1,473 1,002 471 982 732 250

St. Croix

Undergraduate 860 617 243 475 334 141 385 283 102

Graduate 67 55 12 7 4 3 60 51 9

Total 927 672 255 482 338 144 445 334 111

St. Thomas

Undergraduate 1,411 972 439 948 635 313 463 337 126

Graduate 117 90 27 43 29 14 74 61 13

Total 1,528 1,062 466 991 664 327 537 398 139

The Caribbean Green Technology Center at UVI was created in 2011 to advance energy and environmental sustainability in the U.S. Virgin Islands and their neighbors throughout the Caribbean Basin.

IEEE Electr i f icat ion Magazine / March 2015 63

The Solar Power Deployment Initiative at UVIVeriown, inc., the robert W. Galvin center for electricity innovation at illinois institute of technology (iit), and uVi will deploy 3.3 MW of solar power at uVi’s two campuses. (see “uVi’s Partners.”) by the end of 2015, this solar power deployment initiative will reduce uVi’s dependence on fos-sil fuel by 50%. the PV system will use approximately 5.7 acres on the st. thomas campus and 3.9 acres on the albert a. sheen campus on st. croix. this system is expect-ed to produce 5.9 million kWh annually at the st. thomas facility and 2.4 million kWh annually at the st. croix facility.

the u.s. Virgin islands, where uVi is located, have just 110,000 residents, but energy prices are four to five times high-er than those in the continental united states. like many islands, the u.s. Virgin islands are almost 100% dependent on imported oil for electricity and water generation. residents pay about us$0.57/kWh to light their homes and run their appliances, which is 275% higher than the national average per unit cost benchmark of us$0.33/kWh. the solar power deployment initiative will reduce uVi’s electricity price to us$0.34/kWh (a 33% reduction) via distributed solar power and an advanced storage system. the savings are expected to be about us$11 million for the first eight years (a 39% reduction) and about us$37 million for the first 25 years (a 52% reduction).

the solar power deployment initiative is also in line with uVi’s Goes Green initiative, which is a sustainable, environ-mentally friendly initiative that promotes responsible environ-mental policies and practices. the Goes Green initiative cur-rently includes recycling, reusable to-go containers for food, green cleaning, electric vehicles, and alternative energy. through the Goes Green initiative, uVi is exploring various opportunities for the production of solar energy on campus. the initiative signifies an opportunity to unshackle energy

consumers from the grips of traditional models of energy gen-eration and distribution by using distributed solar. it repre-sents the beginning of a new future leading to cleaner, more efficient, reliable, and lower-cost energy solutions for the u.s. Virgin islands. as uVi President david hall says, “energy con-sumption and costs are crippling challenges facing the Virgin islands and the broader caribbean, and this initiative creates a pathway for addressing the problems.” the solar power deployment initiative is “a historic and transformative devel-opment for the university and the Virgin islands,” notes hall,

and “once this project is completed, uVi will have blazed a trail that many uni-versities throughout the world are des-tined to follow.”

Project Design for the Solar Power Deployment Initiative

Project Sitesa summary of the sites and their cor-responding solar capacities is shown in table 3. a bird’s-eye view of the installation site at the st. thomas campus is shown in Figure 8. the site is next to the uVi sports complex, as shown in Figure 9.

Technological Designin the solar power deployment initiative, Veriown will use solar production to lower the cost of energy to uVi by more

Table 3. The Project Sites and capacities.

Site Location ft2 KW

UVI St. Thomas Campus 243,936 2,099

UVI St. Croix Campus 173,673 1,200

Total 417,609 3,299

UVI’s Partners

Veriown

Veriown, Inc. is an innovative energy com-

pany that helps businesses, universities,

governments, and other institutions harness

their on-site distributed solar and other forms of

distributed energy as well as lock in long-term,

predictable energy rates with little to no capital

expense. Veriown has developed and is further

developing clean tech energy systems that are

based around providing power to areas that

currently have high energy costs due to a lack

of production and/or distribution.

The Robert W. Galvin Center

The Robert W. Galvin Center for Electricity innova-

tion at the Illinois Institute of Technology (IIT)

has pursued groundbreaking work in renewable-

energy deployment and microgrid design over

the last decade. It has completed the first phase

of a next-generation smart solar installation on

the IIT microgrid test bed. The demonstration

consisted of a distributed smart solar photo-

voltaic system with battery installation on the

IIT smart microgrid. The project included build-

ing roof sites of various size systems and was

designed to support the demonstration of novel

solar power systems in residential, commercial,

and microgrid environments. The Galvin Center is

pursuing the full scope of its smart solar installa-

tion across 17 buildings on the IIT microgrid.

The U.S. Virgin Islands have a tropical climate, moderated by easterly trade winds and with relatively low humidity.

IEEE Electr i f icat ion Magazine / March 201564

than 40% during peak production hours, defined as the period of time when the solar system is producing power. because solar is not a base load power source, the solar sys-tem is oversized based on electricity consumption require-ments during peak production hours and stores the energy for off-peak production hours, the period of time when the solar system is not producing power, using advanced ener-gy storage. the system is also designed to eliminate the inherent inability of renewable power production to load-follow due to the peak power design or constantly changing input power levels from variations in the sun, wind, or

other production sources. the solar power deployment ini-tiative will develop a 3.3-MW ground-mount crystalline PV system with a single-axis tracker. the system will include the components listed in table 4.

this system design is an ideal platform into which new-technology battery storage should be introduced. table 5 shows the requirements for the energy-storage system. a fully integrated energy-storage system that sat-isfies those requirements should be delivered to the site containerized, prewired, and pretested, reducing site work and installation time. one such solution is available from s&c electric and summarized in table 6. a more detailed description of each component follows.

Power Electronicss&c’s storage Management system (sMs) is an example of a utility-grade power-conversion system. it provides four-quadrant control, acting as either a voltage or current source (adjustable on the fly), with the ability to absorb or provide real and reactive power. as illustrated in Figure 10, the four-quadrant design allows the sMs to manage a wide range of real and reactive power requirements (the points along and within the red dashed line). the control algorithms within the sMs support a wide variety of ener-gy-storage use cases, including peak shaving, dynamic islanding, renewable-energy integration, energy arbitrage, ancillary services (including frequency regulation), load following, and voltage control.

the sMs includes the inverters, ac and dc breakers, and controls mounted within each international organization for standardization (iso) container. the building block of the sMs is an individually controlled ±1.25-MVa/1.0-MW inverter, with a dedicated 480-V breaker for each inverter, as shown in Figure 11. up to four 1-MW inverter blocks can be combined into a single iso container, and a total of 20 MW can be man-aged under a single control. the insulated gate bipolar transis-tor (iGbt) is the major power electronic component within the 1-MW inverter block. each 1-MW inverter block contains 12 iGbts and has its own local control and small ac filter com-ponents to ensure harmonic-free sine waves at the output ter-minals of the inverter. the sMs includes ±500-kW, dc-to-dc converter chopper blocks, which take the variable dc voltage

Table 4. The Proposed PV System components.

System Component Quantity

Yingli/LDK-watt crystalline PV modules 10,920

Fixed-tilt solar panels (5°) 2

260-kW commercial Inverter with complete setup

9

16-circuit subcombiners with 100-A fuses 9

12-circuit combiner boxes 90

Data acquisition system gateways for each inverter

9

Table 5. The requirements for the energy-Storage System.

Element Requirement

Power St. Thomas: 1 MW St. Croix: 500 kW

Energy 3–4 h of storage at rated power

System life 10+ years

Battery functions Time-shifting solar generation

Ambient conditions Tropical/salt in the air

Containerized or indoor

Containerized

Figure 8. A bird’s-eye view of the UVI St. Thomas Campus 2,099-kW dc solar array.

Figure 9. The UVI St. Thomas Campus 2,099-kW dc solar array.

IEEE Electr i f icat ion Magazine / March 2015 65

from the battery and create the fixed dc link voltage for the inverter system. the sMs controls the chopper circuits to allow charging or discharging of the batteries within the rigor-ous requirements provided by the battery manufacturer. the choppers are controlled to determine the direction of power flow and are current-limited by the controls in accordance with the battery controller’s commands.

the digital signal processing–based sMs controls pro-vide efficient operation across a wide range of power lev-els, which is a benefit for variable-power applications, as shown in Figure 12. all of the sMs subsystems are housed in a custom enclosure mounted inside an iso container. a typical sMs iso container without the transformer and batteries is shown in Figure 13.

Batterythe world of energy-storage choices can be complicated. each energy-storage technology presents its own set of pros/cons, maturity level, and costs. table 7 provides a summary the different technologies available today. based on the proj-ect requirements, a lithium-ion battery system has been con-sidered for the st. croix site, and options of both the lithium-ion battery system and a sodium–nickel–chloride (NaNicl) battery system were considered for the st. thomas site. lithi-um-ion batteries, with their combination of high discharge rates, excellent energy density, modularity, and low

Figure 11. The ±1.25-MVA SMS inverter and two choppers. (Image courtesy of S&C Electric, “Storage Management System,” http://sandc.com/products/energy-storage/sms.asp.)

Discharge (kW)Charge (kW)

Capacitive (kvar)

Inductive (kvar)Possible

Combinations ofReal and Reactive

Power

Figure 10. A conceptual four-quadranat power-conversion system. (Image courtesy of S&C Electric, “Storage Management System,” http://sandc.com/products/energy-storage/sms.asp.)

Table 6. The Integrated energy-Storage System Solution.

Item St. Thomas Installation St. Croix Installation

Power Electronics S&C PureWave SMS1.25 MVA/1.0 MW

S&C PureWave SMS-250263 kVA/250 kW

Battery Lithium-ion 3,000 kWh orsodium–nickel–chloride (NaNiCl) 2,400 kWh (Total of 3,000-kWh embedded energy, but limited to 80% depth of discharge)

Lithium-ion2,000 kWh

1009080

70605040302010

00 10 20 30 40 50 60 70 80 90 100

Power (%)

Effi

cien

cy (

%)

SMS Efficiency

Figure 12. An SMS efficiency curve. (Image courtesy of S&C Electric, “Storage Management System,” http://sandc.com/products/energy-storage/sms.asp.)

IEEE Electr i f icat ion Magazine / March 201566

maintenance requirements, are a flexible energy-storage technology appropriate for a variety of applications. NaNicl technology provides an excellent energy density and cycle life without the need for heating, ventilating, and air conditioning systems or other auxiliary loads. in both cases, battery mod-ules are combined into a sophisticated energy-storage system with multiple levels of control and protection. each container includes a dedicated battery- management system (bMs), circuit breaker, and contactors as well as cur-rent and voltage sensors. a master bMs provides control across multiple racks and/or modules. the specifica-tions of the complete battery systems are shown in table 8.

Project Performance Measurestable 9 shows the quantifiable project performance mea-sures that will be achieved as a result of the solar power deployment initiative.

Project Financing for the Solar Power Deployment Initiativein the solar power deployment initiative, Veriown will use solar production to lower the cost of energy to uVi by more than 40% during peak production hours, defined as the period of time when the solar system is producing

power. because solar is not a base load power source, the solar system is oversized based on electricity consumption requirements during these peak production hours and store the energy for off-peak production hours, the period of time when the solar system is not producing

power, using advanced energy stor-age. the system is also designed to eliminate the inherent inability of renewable power production to load-follow due to peak power design or constantly changing input power levels from variations in the sun, wind, or other production sources.

the total budget of the solar power deployment initiative is us$13.136 million, of which us$3 million is sponsored by a u.s. depart-ment of agriculture grant and the

remaining us$10.136 million is cost-shared by Veriown. upon the completion of the initiative, 3.3 MW of solar PVs will be installed and operational at uVi’s two campuses. Veriown will enter into a PPa with uVi. the PPa is a financ-ing arrangement that allows uVi to purchase solar electrici-ty with little to no upfront capital cost. to achieve this, uVi provides unused rooftop, land, or parking lot space as a location for a solar installation. Veriown pays for the cost of the solar installation and assumes all responsibility for ownership, operation, and maintenance once the solar

Table 7. a Summary of currently available energy-Storage Technologies.

TechnologyMaximumCurrent Rate

Energy Density

Cycle Life Calendar Life

Maintenance Requirements

Technology Maturity

Minimum Scale

Lithium-ion High High Medium Medium Low High 1 kW

Lead-acid Medium Low Low Low High High 1 kW

Sodium-sulfur

Low Medium Medium High Low High 1 kW

NaNiCl Medium Medium Medium High Low Medium 100 kW

Flow battery Low Low High High High Low 100 kW

Flywheel High Medium High High Low Medium 200 kW

Table 8. The Desired System-level battery Specifications.

Item St. Croix St. Thomas St. Thomas

Technology Lithium-ion Lithium-ion NaNiCl

Total embedded energy(beginning of life)

2,000 kWh 3,000 kWh 2,400 kWh usable3,000 kWh embedded

Cycle life 6,000 cycles 6,000 cycles 4,500 cycles

Round-trip dc efficiency At least 90% At least 90% At least 90%

Operating temperature range (to be maintained by high-voltage ac system)

23 ± 5 °C 23 ± 5 °C −10 °C to +40 °C

S&C’s Storage Management System is an example of a utility-grade power-conversion system.

IEEE Electr i f icat ion Magazine / March 2015 67

project is complete. the well-structured PPa allows uVi to reduce electricity costs immediately (from us$0.51/kWh to us$0.34/kWh, a 33% reduction) and realize increased savings over time as grid elec-tricity prices rise.

Figure 14 shows a detailed PPa cash flow analysis over the next 25 years, assuming an initial PPa rate of us$0.34/kWh, a PPa escalator of 3%, and an annual utility elec-tric rate increase of 5%. in summary, the avoided electricity cost for the first ten years is us$11,057,098 (a 46% reduction) and for the first 25 years is us$47,577,968 (a 58% reduction). additional benefits of the PPa include 1) no initial capital investment because uVi only pays for the solar electricity that is produced after installation, 2) fixed energy rates as the PPa provides a powerful hedge against volatile electricity prices, 3) uVi is not responsible for system operation or maintenance, and 4) a benefit from solar tax credits in the form of a lower PPa rate.

For Further readingcentral intelligence agency. (2014). the World Factbook: u.s. Virgin islands. [online]. available: https://www.cia.gov/library/publications/the-world-factbook/geos/vq.html

e. lantz, d. olis, and a. Warren, “u.s. Virgin islands energy road map: analysis,” National renewable energy laboratory, Nrel/tP-7a20-52360, sept. 2011.

s&c electric, (2014). “storage Management system,” http://sandc.com/products/energy-storage/sms.asp

siemens Pti. (2011). report r59-11: ViWaPa interconnection feasibility study final report. [online]. available: http://www. viwapa.vi/aboutus/Projects/Projectdetails/11-08-02/usVi-bVi-Puerto_rico_interconnection.aspx

u.s. census bureau. (2003). u.s. Virgin islands: 2000 social, economic, and housing characteristics. [online]. available: http://www.census.gov/prod/cen2000/phc-4-vi.pdf

u.s. census bureau. (2010). income, poverty, and health insurance coverage in the united states: 2009. [online].

available: http://www.census.gov/prod/2010pubs/p60-238.pdf

Wikipedia. (2014). united states Virgin islands. [online]. available: http://en.wikipedia.org/wiki/united_states_ Virgin_islands

biographiesWayne Archibald (warchib@uvi.edu) is an assistant profes-sor and the director of the caribbean Green technology center at the university of the Virgin islands.

Zuyi Li (lizu@iit.edu) is a professor and the associate director of the Galvin center for electricity innovation at the illinois institute of technology, chicago.

Mohammad Shahidehpour (ms@iit.edu) is the bodine chair Professor and director of the Galvin center at the illinois institute of technology in chicago. he is also a research professor with the renewable energy research Group, King abdulaziz university, Jeddah, saudi arabia.

Steve Johanns (steve@veriown.com) is the cofounder and chief executive officer of Veriown in chicago, illinois.

Tom Levitsky (tlevitsky@veriown.com) is the vice presi-dent of operations at Veriown in chicago, illinois.

Figure 13. A 2-MW SMS in a 30-ft ISO container. (Image courtesy of S&C Electric, “Storage Management System,” http://sandc.com/products/energy-storage/sms.asp.)

Figure 14. The PPA reducing the UVI cost of electricity relative to increasing utility energy cost.

6,000,0005,000,000

4,000,000

3,000,000

2,000,000

1,000,000

Cos

t of E

lect

ricity

($)

2014 2019 2024 2029 2034

Cost of Electricity with SolarCost of Utility at 5% Energy Inflation

Table 9. Project Performance Measure.

Performance Measure Target

Renewable energy installed capacity (kW) 3,300

Renewable energy produced (kWh annually) 5,900,000

UVI electricity price (cents/kWh) 34

Potential for CO2 reduction (metric tons annually) 2,000

Jobs created 10

Jobs retained 20

U.S. Department of Agriculture funds (US$) 3,000,000

Funds leveraged (US$) 10,136,000